The aim of the program is to study the physiology, pharmacology, pathology, epidemiology, and clinical picture of heart disease in the young, principally, but not exclusively, relating to congenital heart disease. The clinical aspects of the projects concern themselves with the incidence, mortality, and clinical course of congenital malformations of the heart, as well as the diagnosis by various invasive and non-invasive methods, particularly echocardiography. Pathologic studies, on a large number of heart specimens from this institution, as well as other centers from all over the world, aim at elucidating the embryologic origins of the malformations. In addition, morphologic and physiologic studies of the pulmonary vasculature are being undertaken, in part as diagnostic tools for the quantitation of pulmonary vascular obstruction, and in part to increase our understanding of the nature of pulmonary vascular disease under a variety of physiologic conditions. The pharmacologic and physiologic studies in grown dogs and sheep, fetal as well as newborn lambs, aim at analysing the mechanisms of action of a variety of conditions and agents, particularly vasoconstrictors as well as the reflex control of the circulation at varying ages. Finally, physiologic studies on isolated donor perfused, dog and rat heart preparations are used to investigate the development and regression of cardiac hypertrophy.